Arrangement for oscillation circuits



Dec. 6, 1932. w. RUNGE ARRANGEMENT FOR OSCILLATION CIRCUITS Original Filed Nov. 6. 1925 INVENTOR WILHELM RUNGE ORNEY Patented Dec. 6, 1932 umrao STATES PATENT. OFFICE WILHELH BUNGE, OF BERLIN, GERMANY, ABSIGNOR '1'0 TELEFUNKEN GESELLSOH AFT I'UB DBAHTLOSE TELEGBAP-HIE MIT BESCHBANKTER HAF'IUNG, OI BERLIN, GER- NY, A CORPORATION OI GERMANY ARRANGEMENT FOR OSCILLATION CIRCUITS Application filed November 8, 1925, Serial No. 67,208. Renewed November 7, 1930.

The object of the invention is to provide means whereby the differential beat frequency resulting from two oscillation circuits is kept constant during equal changes in tunin means.

further object of the invention is tq provide means whereby at a single setting, for instance, the turning of a knob or handle, the beat frequency of two cooperating oscillatdion circuits preserves a constant magnitu e.

Other objects of the invention will appear more fully hereinafter as shown in the accompanying drawing, and' finally pointed out 16 in the appended claims.

Referring to the drawing, Fig. 1 shows an embodiment of an arrangement conformable with the present invention.

Fig. 2 is a diagram showing a gra h wherezo in the dependence of the resonance requency of an oscillation circuit u on the reciprocal value of a capacity and t 1eir functions,is exhibited.

Fig. 3 is a diagrammatic sketch wherein inductance values are substituted for the variable capacity. Fig. 4 shows the means for adjusting the variable condensers. In connection with the service 7 work and the various problems encountered in high frequency work it is often essential that the difference in frequency of oscillations of two high frequency circuits should be kept constant over variable wave ranges. A change from one wave range to another wave range as ordinarily requires separate setting of tuning means in each of the two circuits. In many cases separate adjustment of the tuning means in each of the circuits is rather tedions and inconvenient.

One of the problems to be solved by the resent invention is that by a single setting as or example the turning of a knob or handle as set forth below the beat frequency of two oscillation circuits, which may be varied, is

maintained constant. An illustrated embodiment of the invention consists in that one of the two oscillation circuits is an inductance and a condenser of the rotary type, and the other oscillation circuit is an inductance of somewhat lower value, a rotary condenser, and a fixed condenser in series with the latter. It can be proved that with a proper proportioning of the circuits, a synchronous turning of the two condensers or other'tuning elements may be made to yield a differential beat whose frequency remains appreciably constant. The circuits shown in Fig. 1 illustrate a self-inductance L and a capacity C, while the other circuit possesses a selfinductance of lesser value L and a capacity which is determined by the series connection of the two condensers with capacities C, and

is plotted for. the case where the oscillation circuit contains in addition the series capacity (3,, there results a displacement of the parabolic curve along the abscissa by an amount as shown by curve 2, which constitutes a function of the frequency and l -1 We. The shape of the parabola (its focal distance) depends itself upon the value of the self-inductance which represents the parameter. Hence, by a convenient selection of the self-inductance,'it is easy-to change curve 2 into curve 3. Curve 1, therefore, represents the frequency'depending upon the change 11'! capacity in an oscillation circuit such as circuit 1 in Fig. 1, and curve 3 shows the frequency dependence of an osc llation circuit corresponding to circuit 2, Fig. 1, upon the analogous setting of the corresponding rotary condenserin this circuit. Hence, the relation holding for the circuit 1 is was and the relation for circuit 2 is As can be inferred from numerical examples and as diagrammatically shown in the graph, the difference of. the frequencies of the two circuits inside a frequency range lying approximately between points A and B, 1s near- 1y constant. It is, therefore, ossible by means of an arrangement of the ind shown and built in conformity with the basic idea of the invention, to mount the two condensers upon a common axis or spindle and to vary the tuning in the two circuits by turning one knob in such a manner that the difference of their frequencies remains well night unvaried. Figure 4 shows the two variable condensers 0,. having their movable plates 1 mounted upon a common spindle 2 which is rovided with an adjusting knob 3 at one end or simultaneously adjusting the condensers. A corresponding result is attainable also by other means, for example, in one of the I circuits a variomete'r is exhibited in lieu of a rotary condenser, and instead of the fixed self-inductance coil a fixed condenser. Also in circuit 2 in lieu of the series connection of the fixed and the variable condenser a parallel connection maybe substituted consisting of a low and a high self-inductance. In an arrangement of this kind the functions of L and C are exchanged as can be seen by comparison of the relations between the two circuits.

A very important application of the present invention is in beat reception arrangements, for instance, telephone reception apparatus working with intermediate beat fre uency. One of the oscillation circuits in t is case is the circuit to which the incoming high frequency oscillations are supplied while thesecond circuit is the oscillation circuit of the local high frequency generator whose oscillations are superposed upon the incoming high frequency oscillations, rectification of the oscillatory currents being then made.

By a single adjustment it is then possible to effect the tuning of the radio receiving circuit as well as to maintain constant the beat frequency of the intermediate or differential frequency.

Having now set forth the object and nature ful and desire to secure by Letters Patent is,

1. In a heterodyne receiving system, the combination of a receiving circuit and a local oscillation circuit, one of said circuits including an inductance, a fixed condenser and a variable condenser and the other of said circuits including only an'inductance and an equal variable condenser, said variable condensers being of substantially similar characteristics throughout the range of variation and common means for adjusting said variable condensers by equal amounts, the values of said fixed and variable condensers being so related that a beat frequency of substantially constant value is produced by adjustment of said variable condensers, the inductance in one of said circuits being greater than the inductance in the other.

- inductance in the oscillation circuit being less than the inductance in the receiving circuit.

3. A superheterodyne receiving arrangement comprising a. receiving circuit and a local oscillation circuit, one of said circuits including an inductance, a fixed condenser and a variable condenser and the other circuit including an inductance and a variable, condenser substantially equal to said first named variable condenser, said variable condensers.

being of substantially similar characteristics throughout the tuning range and a sin 1e control means for adjusting said varia le condensers by equal amounts, said fixed and variable condensers having such relative values that a high intermediate beat frequency of substantially constant value is produced by adjustment of said variable condensers through a limited tuning range, the inductance in one of said circuits being greater than the inductance in the other.

4. A superheterodyne receiver for telephone signals, comprising a receivin circuit including an inductance and a varia le condenser, a local oscillation circuit coupled to the receiving circuit including an indutance, a fixed condenser and a variable condenser connected in series, the capacities of said variable condensers being equal and said variable condensers being equally adjusted by one of my invention what I claim as new and usecontrol means,said fixed and variable condensers having such relative values that an intermediate beat frequency of approximate- 1y constant value is produced as the receiving circuit is tuned to an incoming signal by sald control means, the ratio between said inductance having a value other than unity.

W. RUNGE. 

